many americans, the swarm of bikers and a young family in the car. Also tonight an exclusive interview with the young man who was reportedly at the center when the whole thing started. Tonight he walks abc's dan harris through that tape. Reporter: Tonight, a new arrest in the attack in alexian lien and his family. Craig white is the first person to be accused of the actual beating. It come amid a widening police investigation into whether off duty cops riding with the group witnessed the violence but did nothing to stop it. One undercover detective has been placed on desk duty. Meanwhile, we sat down for an exclusive interview with the biker accused of kicking off the whole thing by pulling in front of the suv and slowing down to provoke a fender bender, which led to the initial confrontation in which alexian lien pulled out, seriously injured one biker and then was chased and beaten. Do you feel in any way responsible for what happened after that accident? I don't think -- I feel responsible, but I do feel -- i do feel bad for that family that got hurt. Reporter: Christopher cruz insists he never tried to pick a fight with lien. Walk me through the tape. Reporter: Cruz says what you see here is simply him trying to change lanes. And those looks over his shoulder? That's him searching for his friends. It looks like you're trying to slow him down. I never had intentions to slow him down or cause any type of problems. Reporter: Cruz points out that his break light never went on. Reporter: So basically this is just a big understanding? Very big misunderstanding. Reporter: Police clearly aren't buying it. Cruz faces several charges, including reckless endangerment. It has turnlife upside down right now. Reporter: Are you worried about what happens next? Yes, I am. Dan harris, abc news, w york.

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